Linear multiple feeder for automatic surface-mounting device positioning apparatuses

ABSTRACT

A linear multiple feeder for use with machines for automatically positioning surface-mounted devices (SMDs) collected from a tape wound on a reel. The tape has a protective film coating removably attached thereto, and detachable therefrom for enabling the device to be picked-up. The feeder comprises a support structure, a plurality of reels of tape carrying the device revolvingly mounted to the structure, motor-driven wheels for retrieving the protective film being detached from the tape to expose those components that are ready for collection, a plurality of relatively parallel lanes on the support structure, downstream from the film-retrieving wheels. Also provided is a device for forward linear delivery of the tape along the lanes. The delivery device includes a carriage moving alternately between two stops and carrying a row of tape-entraining pins selectively engageable with holes in the tape and inside the lanes so as to induce forward motion of only those tapes selected. The lanes are provided with respective elements for separating the film coating entrained axially by the film-retrieving wheels in a direction opposite to that of forward feed delivery of the corresponding tape, thereby detaching the film coating from the tape as the latter moves forward by forcing it against the separator elements. The tension induced in the film coating by the film-retrieving wheels biases the separators against the bottom of their respective lanes so as to prevent movement of any tape(s) that have not been selected by blocking them between the separators and the bottom of the lanes.

FIELD OF THE INVENTION

The present invention relates generally to the production of electronic components and, more particularly, to surface-mounting technologies and the like.

BACKGROUND OF THE INVENTION

Conventional surface-mounting technologies, as are often used in the manufacture of electronic circuits, involve the use of surface mounted devices (SMDs) of increasingly limited dimensions. SMDs are typically installed using computer-controlled automatic “pick and place” type machines with one or more picking and placing heads, which collect the components from suitable feeders and deposit them in a selected position on a printed circuit board or the like.

Feeders are used to make the SMD ready for collection from their packaging. The feeders open the packages and present the components at a required position so that they can be collected by a positioning head.

There are various types of packaging, the most widespread of which is the type using tape wound on reels. In this case, the feeder is used to feed the tape forward by means of holes punched in the tape and to separate and wind up the film applied over the tape to cover the recesses containing the components.

Two main solutions have been developed to feed the tape forward and retrieve the film: the first involves the tape being driven forward by the stepping rotation of a gear wheel; the second involves a system using linear actuators.

Pneumatic actuators have been used in the gear wheel delivery systems, in which levering devices are used to turn the gear wheel to feed the tape carrying the SMD forward and simultaneously operate a system that retrieves the film. Electrical actuators have also been used instead of pneumatic actuators. Linear delivery systems generally involve the use of a linear electric actuator, which drives a carriage complete with retractable pins designed to engage in the holes in the tape, and thereby entrain the tape together with the carriage, and then become disengaged therefrom at the beginning of the carriage's return stroke. Such solutions have been used both for single feeders, i.e. where each tape is installed on a separate delivery device, and for multiple feeders, i.e. where several tapes are contained in the same unit and a common actuator is used to drive them forward with a system for selecting only the tape(s) that have been programmed for delivery.

The main drawback of the above described feeder systems lies in that highly complex configurations are necessary to obtain a high operating precision, with consequently high costs. In the case of the gear wheel type of feeder, moreover, the wheel must be able to engage in tapes of different thicknesses around an arc of a circle, which means that some degree of slack must be allowed between the diameter of the tooth and a hole in the tape: this poses problems of positioning repeatability when different tapes are used. Moreover, in the case of a machine with single-actuating feeders having to perform multiple pickups, i.e. when the machine's pickup heads descend simultaneously onto a number of exposed SMD, a mechanical adjustment system is needed to enable the alignment of the different feeders. Therefore, in machines with gear wheel type multiple feeders, adjustment means have to be provided on each wheel to guarantee the precision needed for multiple pickups.

In a linear feed multiple feeder of known type, a mechanical housing structure contains a linear electrical actuator capable of driving a carriage with a plurality of retractable pins, i.e. that rise and fall due to the effect of respective electromagnetic actuators. The selective engagement of the pins enables only the required tapes to be move forward together with the carriage. After the forward motion the activated carriage returns to the resting position. In this type of feeder, the film covering the SMD is lifted away from one side to enable the component to be picked up and the film exits from the front of the feeder, still attached to the tape, which is now empty on the other side. In practical terms, as the tape moves forward, it encounters a shaped blade that detaches the film from the tape along one side of the latter, raising it enough to expose the SMD. This solution entails a significant increase in the dimensions and structural complexity of the feeder, while failing to eliminate the risk of the tape moving. In addition, the tapes are more complicated to feed and the system is sensitive to any differences in the way the film is attached to the tape as a result of manufacturing defects or aging of the adhesive.

OBJECTS AND SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a linear multiple feeder for automatic SMD positioning machines that enables highly precise exposure of the desired electronic components for simultaneous pickup and, thereby, ensuring that a plurality of pickup heads descend onto the feeder simultaneously so as to collect a selected number of suitably exposed and perfectly aligned SMD.

Another object of the present invention is to provide a linear multiple feeder of the aforesaid type that is less expensive and smaller in size than comparable feeders of known type with an equivalent performance.

A further object of the present invention is to provide a linear multiple feeder of the aforesaid type whose reliability and precision are unaffected by highly numerous operating cycles.

These objects are achieved by the linear multiple feeder according to the present invention, the essential characteristics of which are set forth in claim 1. Further important features are set forth in the dependent claims.

The linear multiple feeder for SMD automatic positioning machines according to the invention comprises a supporting structure, a plurality of reels of tapes carrying the SMD revolvingly installed on the supporting structure, means for the retrieval of the protective film detached from the tapes when the SMD components are exposed for collection, a plurality of parallel lanes for the delivery of the tapes provided on the supporting structure, downstream from the means for retrieving the film, and a device for the linear forward delivery of the tapes along the lanes, comprising a carriage alternately moving between two stops and carrying a row of tape-entraining pins selectively engageable in the tapes inside the lanes so as to carry only the selected tapes forward as necessary. In the lanes there are respective elements for separating the coating film, which is axially drawn along by the retrieval means, in the opposite direction to the delivery of the respective tape, in order to detach the film from the forward-moving tape, forcing it against the separator elements, the tension created in the coating film by film retrieval means being suitable for pushing the separators against the bottom of their respective lanes and thereby prevent any movement of the tapes that have not been selected for delivery, by locking them between the separators and the bottom of the lane.

BRIEF DESCRIPTION OF THE DRAWINGS

A specific, illustrative linear multiple feeder for automatic SMD positioning machines, according to the present invention, is described below with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a linear multiple feeder for automatic SMD positioning machines, according to one aspect of the present invention;

FIG. 2 shows a partial lateral cross-section of the feeder illustrated in FIG. 1;

FIG. 3 is an enlarged perspective view of a front portion of the feeder shown in FIG. 1;

FIG. 4 is a sectional view taken longitudinally of the feeder shown in FIG. 1;

FIG. 5 is a plan view of the front portion shown in FIG. 3; and

FIG. 6 is an enlarged view of a side wall of a pick-up station, according to one aspect of the present invention.

Still other objects and advantages of the present invention will become apparent from the following description of the preferred embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings and, more particularly, to FIGS. 1-6, there is shown generally a specific, illustrative linear multiple feeder for automatic surface-mounting device (SMD) positioning machines, according to various aspects of the present invention. In one embodiment, illustrated in FIGS. 1-3, the feeder has a relatively rigid, box-like frame comprising a base portion la, an upright portion 1 b rising from the base portion, and a top portion 1 c extending generally horizontally from a free end of the upright portion. Inside upright portion 1 b, reels 2, 3 are desirably mounted revolvingly on respective spindles 4, 5 supported on either side, preferably at two different heights, by the upright portion. It is preferred that the reels be staggered relatively vertically so as to avoid any interference between tape(s) containing the SMD being unwound therefrom. At an upper end of upright portion 1 b, generally at the same height as top portion 1 c, a shaft 7 is provided on which a battery of driving wheels 6 is integrally mounted for retrieving a film coating detached from the tape containing the SMD. The shaft is connected to a geared motor 8 by a traditional pulley transmission system (not shown) having a geared wheel 9, shown in FIG. 2.

With reference also to FIG. 5, the top portion 1 c comprises a horizontal bed 10 containing a plurality of longitudinal lanes 11, lying parallel to one another for the controlled feeding of the tape carrying the components towards a pickup area generically indicated by the numeral 12, situated at the free end of the top portion 1 c. Inside the latter, underneath the bed 10, there is a device for feeding the tape forward, indicated generically by the reference number 13. The lanes also contain respective film separators 14 consisting of suitably shaped bars, described in more detail later on.

With particular reference to FIGS. 3 and 4, the delivery device 13 comprises an actuator 15, which is pneumatic in the present embodiment of the invention, solidly attached to the bed 10 with a mobile stem 16 connected by means of a bracket 20 to a transverse carriage 17 and to a block 21 sliding inside a guide (not shown) that is integral to the bed 10. The carriage is longitudinally movable between two stops 18 and 19.

Inside the carriage 17, there is a row of pins 22 into a crosswise arrangement. The pins 22 have a body 22 a that fits inside a seat 23 in the carriage 17 and they are designed so that their pointed end projects from a head 17 a extending crosswise over the carriage 17. The pins 22 are arranged vertically with their pointed ends facing the lanes 11 and they are axially mobile within the carriage 17 so that they can selectively engage in or be disengaged from the guide holes aligned along at least one side of the tape carrying the SMD, a length of which (indicated by the letter N) is shown in FIG. 5. The axial movement of the pins 22 is controlled by pneumatic actuators 24.

The sliding lanes 11 have side walls 25 between which the film separators 14 are installed. As shown in detail in FIG. 6, the walls 25 frontally (i.e. in the area facing the pickup section 12) present an edge 25 a that slopes in the opposite direction with respect to the pickup section 12 and, towards the bottom of the respective lane, against which a blocking pin 26 (that extends across the front end 14 a of the separator 14) abuts. The end 14 a of the separator 14 is substantially wedge-shaped so as to guide the coating film, which slides over the separator 14, coming up against its end 14 a, after it has been detached from the tape carrying the SMD as a result of the tensile stress brought to bear by the respective film rewinding wheel 6 on which it is retrieved.

The opposite edge 25 b of the walls 25 slopes in the opposite direction to edge 25 a and serves as a striker for a second transverse pin 27 connected to a spring (not shown) contained longitudinally inside the separator 14.

The feeder according to the invention functions as explained below.

In the condition when the feeder is at rest, the tapes containing the SMD are placed inside respective lanes 11 and the protective film, already partly detached from the respective tapes, passes over the separators 14 and is wound around respective film-retrieving driving wheels, which are at a standstill. The carriage 17 is in its withdrawn position up against the rear stop 18, and the pins 22 are each engaged in a hole in the respective tape.

When a delivery signal is issued, the geared motor 8 turns the film-retrieving driving wheels 6, which draw the coating film taut. The tension on the film comes to bear on the ends 14 a of the separators 14, which are thus drawn back. Given the restraining effect of the blocking pins 26 abutting against the sloping edges 25 a, which makes the pins 26 slide along said edges, the separators 14 re pushed downwards and come to rest on the tapes, holding them pressed against the bottom of their respective lanes 11. Meanwhile, the tape-entraining pins 22 are withdrawn inside the carriage 17 to disengage them from the respective tapes with the exception of those engaged in the tapes selected for delivery. The carriage 17 advances to the front stop 19 entraining the tapes in which the selected pins 22 have remained engaged, while the drive wheels 6 continue ot keep the film pull taut.

Once the SMD have been collected, the tape-entraining pins 22 engaged in the selected tapes drop back into the carriage 17, thus becoming disengaged from the tape, and the carriage returns to the opposite end of its stroke 18, while the drive wheels 6 ensure the retrieval of the film detached from the selected tapes as a result of the delivery stroke. Then all the tape-entraining pins 22 reemerge, hooking up the tapes again, while the film retrieving drive wheels 6 stop and the feeder returns to its resting condition, ready for a new feeding cycle.

Thus, the tapes that do not need to move forward are kept at a standstill by the separators 14 due to the effect of the tension on the films, which would normally tend to displace them. This ensures the utmost precision and repeatability of the delivery cycles because the tapes that do not need to advance are hold in place, ensuring that there is no, even minimal movement on their part that could prevent the subsequent engagement of the tape-entraining pins in the holes in the tapes when the carriage is drawn back.

The second pin 27 exerts an auxiliary tensile action in the same direction as the one brought to bear by the film-retrieving wheels 6. This auxiliary action is useful both to reinforce the downward thrust towards the bottom of the lanes 11, which helps to hold the tapes fast therein and to compensate for any (ultimately unavoidable) discrepancy in the turning speeds of the film-retrieving wheels 6. Finally, the combined and opposing action of the transverse pins 26 and 27 ensures the stable positioning of the separators 14 inside their respective lanes 11, preventing their accidental or unwanted displacement.

It should be noted, moreover, that the provision of a movement of the carriage 17 with a fixed stroke between the two stops 18 and 19 contributes simply and reliably to ensuring an excellent repeatability of exposure of the components. In addition, the assembly of the tapes on the feeder is straightforward and practical because the film separators are simply rested on the tapes and can consequently be promptly removed from their respective lanes, to allow for the positioning of the tapes, and then put back in place.

Various modifications and alterations may be appreciated based on a review of this disclosure. These changes and additions are intended to be within the scope and spirit of the invention as defined by the following claims. 

1. A linear multiple feeder for surface-mounted device automatic positioning machines, the device being arranged on a tape and wound about a reel, and the tape having a protective film coating removably attached thereto, and separable therefrom for enabling the said SMD device to be collected, the feeder comprising a support structure, a plurality of reels of tape carrying the device revolvingly mounted to the structure, a member for retrieving the protective film detached from the tape when the components are exposed for collection, a plurality of relatively parallel lanes on the supporting structure, downstream of the film-retrieving member, a device for forward linear delivery of the tape along the lanes, the delivery device including a carriage moving alternately between two stops and carrying a row of tape-entraining pins selectively engageable with holes in the tape and inside the lanes so as to carry forward only those tapes selected, wherein respective elements between the lanes for separating the film coating, drawn along axially by the film-retrieving member, in a direction opposite to that of delivery of the respective tape, in order to detach the film coating from the forward-moving tape, and forcing it against the separator elements, whereby the tension created in the film coating by the film-retrieving member is suitable for biasing the separators against the bottom of their respective lanes and, thereby, preventing movement of those tapes that have not been selected for delivery, by blocking them between the separators and the bottom of the lane.
 2. The multiple feeder set forth in claim 1, wherein the front end of the separator elements abuts the respective film under tensile stress, at least one locking pin extending generally crosswise from the end and abutting an edge of a side wall of the respective lane, the edge sloping in the direction opposite to that of forward delivery of the tape in the lane and leading downwardly toward the bottom of the lane.
 3. The multiple feeder set forth in claim 1, wherein a lateral wall of each lane has a further edge that slopes in a direction opposite to the one that the blocking pin abuts, a further transverse pin being provided at a rear end of the separators that abuts the sloping edge, the transverse pin being elastically joined to the respective separator to force against the further edge.
 4. The multiple feeder set forth in claim 1, wherein the film-retrieving member comprises respective coaxial drive wheels on the supporting structure and operatively associated with a motor.
 5. The multiple feeder set forth in claim 1, wherein the stops include a plurality of fixed abutment elements.
 6. The multiple feeder set forth in claim 1, wherein the front end of the separator elements, on which the relevant tensioned films abut, is substantially wedge shaped. 